M7.L2 — Wiring & Parameter Cheat Sheet
Module 7 · Lesson 2
Wiring & Parameter Cheat Sheet
Advanced Motor Control & Drives Mastery — Book 3 of the Electrical Series
How to use this lesson: This consolidates the wiring and parameter reference tables from across the whole
book into one place — for the reasoning and full context behind each entry, revisit the lesson it's drawn from.
Use the tabs below as an on-the-job quick lookup, not a replacement for understanding the "why" behind each item.
VFD Terminals
VFD Parameters
Soft Starter
Servo/Motion
Diagnostics
Power Terminals (Module 1, Lesson 4)
| Terminal | Function |
|---|
| R / S / T | Mains input (3φ) — incoming supply only, never output |
| U / V / W | Motor output (3φ) — variable voltage/frequency, never mains input |
| +DC / −DC | DC bus terminals — lethal voltage may remain after power removal |
| DB / B1,B2 | Braking resistor terminals |
| PE | Protective earth — both at drive and motor frame |
Control I/O (Module 1, Lesson 4)
| Type | Typical Labels |
|---|
| Digital Input | FWD, REV, RST (Fault Reset), MS1-3 (multi-speed), EXT FAULT |
| Analog Input | AI1 (0-10V), AI2 (4-20mA), GND/COM |
| Relay/Digital Output | RUN, READY, FAULT (Form C: NO/NC/COM), AT SPEED |
| Analog Output | AO1, AO COM |
| Comms | RS485 (A/B), Ethernet port |
Core Commissioning Parameters (Module 1, Lessons 2-3, 5)
| Parameter | Guidance |
|---|
| Accel/Decel Time | Match to load inertia and current limit — too fast trips overcurrent/overvoltage, too slow wastes process time and overheats the motor |
| V/Hz vs. Vector Mode | V/Hz for simple fan/pump loads; Vector for high starting torque at low speed or precise regulation |
| Motor Auto-Tune | Run before first production start on vector-controlled drives — required for accurate torque control |
| Current Limit | Set to actual load requirement, not drive maximum — this is your first layer of stall protection |
| Braking Method | DC injection for occasional low-inertia stops; resistor for regular/high-inertia decel; regenerative for continuous overhauling loads |
Soft Starter Parameters (Module 2, Lesson 1)
| Parameter | Guidance |
|---|
| Initial Torque/Voltage | Just high enough to overcome static friction and begin rotation smoothly |
| Ramp Time | Match to load's smooth acceleration need — check against motor thermal/starts-per-hour limits |
| Current Limit | Caps starting current regardless of torque demand — verify against supply capacity |
| Kickstart/Pulse | Use for heavy/sticky loads needing extra torque to break static friction |
| Stop Mode | Soft stop for pumps (prevents water hammer); coast for most fan/conveyor loads |
Wiring Configs
| Config | When Used |
|---|
| In-line, no bypass | Lighter duty, infrequent starts |
| In-line with bypass | Standard for continuous-duty motors |
| Inside-the-delta (6-wire) | Motor delta-connected, all 6 leads accessible — SCRs see winding current (line ÷ √3) |
Servo Commissioning Order (Module 3, Lesson 1)
| Step | Action |
|---|
| 1 | Verify mechanical install (coupling torqued, guards fitted) |
| 2 | Confirm encoder wiring and shield termination |
| 3 | Power up with motor disabled — check for immediate feedback faults |
| 4 | Jog at low speed/torque — confirm direction sense |
| 5 | Run auto-tune/inertia estimation |
| 6 | Design and test homing sequence (incremental feedback) |
| 7 | Slow, low-load test move across full travel range |
Tuning Symptom Reference (Module 3, Lesson 2)
| Symptom | Adjustment |
|---|
| Sluggish response | Increase P |
| Overshoots then settles | Increase D first; reduce P if it persists |
| Continuous oscillation | Reduce P significantly |
| Small steady-state offset | Increase I slightly |
| Slow wobble after settling | Reduce I |
Megger Guidelines (Module 4, Lesson 1)
| Reading Pattern | Interpretation |
|---|
| Near zero | Clear fault — do not energize |
| Low, below guideline | Investigate moisture/contamination/damage |
| Marginal | Trend over time rather than judging on one reading |
| High, comfortably above guideline | Healthy — record as baseline |
Vibration Signature Reference (Module 4, Lesson 2)
| Pattern | Likely Cause |
|---|
| 1× speed, radial | Rotor imbalance |
| 2× speed, radial | Parallel (offset) misalignment |
| 1×/2×, axial | Angular misalignment |
| High frequency, no clear order | Bearing defect frequency |
| Changes significantly with load | Resonance, soft foot, or broken rotor bar |
Knowledge Check
1. Which terminal pair should never have incoming mains connected to it on a VFD?
R / S / T
U / V / W
PE
2. On a servo axis, continuous oscillation that never settles calls for which adjustment first?
Increase Integral gain
Reduce Proportional gain significantly
Increase Derivative gain only
3. A megger reading is marginal but technically above the minimum guideline. What's the correct response?
Ignore it since it passed
Trend it over time rather than relying on a single reading
Immediately replace the motor
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